Methods of forming memory cells

ABSTRACT

Some embodiments include methods of forming memory cells. A series of rails is formed to include bottom electrode contact material. Sacrificial material is patterned into a series of lines that cross the series of rails. A pattern of the series of lines is transferred into the bottom electrode contact material. At least a portion of the sacrificial material is subsequently replaced with top electrode material. Some embodiments include memory arrays that contain a second series of electrically conductive lines crossing a first series of electrically conductive lines. Memory cells are at locations where the electrically conductive lines of the second series overlap the electrically conductive lines of the first series. First and second memory cell materials are within the memory cell locations. The first memory cell material is configured as planar sheets and the second memory cell material is configured as upwardly-opening containers.

TECHNICAL FIELD

Memory arrays and methods of forming memory cells.

BACKGROUND

Memory is one type of integrated circuitry, and is used in computersystems for storing data. Integrated memory is usually fabricated in oneor more arrays of individual memory cells. The memory cells areconfigured to retain or store memory in at least two differentselectable states. In a binary system, the states are considered aseither a “0” or a “1”. In other systems, at least some individual memorycells may be configured to store more than two levels or states ofinformation.

Integrated circuit fabrication continues to strive to produce smallerand denser integrated circuits. Accordingly, there has been substantialinterest in memory cells that can be utilized in cross-pointarchitectures. Example types of memory cells that are suitable forutilization in cross-point architectures are resistive RAM (RRAM) cells,phase change RAM (PCRAM) cells, and programmable metallization cells(PMCs)—which may be alternatively referred to as a conductive bridgingRAM (CBRAM) cells, nanobridge memory cells, or electrolyte memory cells.The memory cell types are not mutually exclusive. For example, RRAM maybe considered to encompass PCRAM and PMCs.

The cross-point architectures may comprise memory cell material betweena pair of electrodes. Various problems can be encountered in thedevelopment of such architectures. The problems can involve, forexample, mask misalignment during the various patterning steps utilizedto pattern the electrodes and the memory cell material. Each electrodemay be patterned with a separate masking step, and the memory cellmaterial may be patterned with yet another masking step. Thus, there canbe at least three masking steps to align during the fabrication of thememory cells. As another example, the problems may involve difficultiesin utilizing some types of memory cell materials. For instance, somememory cell materials comprise oxides which are reactive toward manyconductive materials. Thus it can be desired to use noble metals (forinstance, platinum, silver, etc.) in electrodes that contact suchoxides. However, the non-reactivity of the noble metals can make themdifficult to pattern.

It would be desirable to develop improvements in memory cell fabricationwhich alleviate one or more of the above-discussed problems, and todevelop improved memory cells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-7 are diagrammatic three-dimensional views of a portion of aconstruction shown at various process stages of an example embodimentmethod of fabricating memory cells.

FIGS. 8-12 are diagrammatic three-dimensional views of a portion of aconstruction shown at various process stages of another exampleembodiment method of fabricating memory cells.

FIGS. 13 and 14 are diagrammatic three-dimensional views of a portion ofa construction shown at various process stages of another exampleembodiment method of fabricating memory cells.

FIG. 15 is a diagrammatic three-dimensional view of a portion of aconstruction shown at a process stage of another example embodimentmethod of fabricating memory cells.

FIG. 16 is a diagrammatic three-dimensional view of a portion of aconstruction shown at a process stage of another example embodimentmethod of fabricating memory cells.

FIGS. 17-23 are diagrammatic three-dimensional views of a portion of aconstruction shown at various process stages of another exampleembodiment method of fabricating memory cells.

FIG. 24 is a diagrammatic three-dimensional view of a portion of aconstruction shown at a process stage of another example embodimentmethod of fabricating memory cells.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In some embodiments, the invention includes a two-mask, damascene schemethat may be utilized for forming cross-point memory. In someembodiments, the scheme may be utilized for patterning select devices(for instance, diodes, transistors, etc.) in addition to memory cells;and in some embodiments the scheme may be utilized for patterning memorycells separate from select devices. The scheme may be utilized forpatterning noble metals, and may be utilized in combination withpitch-multiplication technologies. In some embodiments, the scheme maybe utilized for forming highly integrated memory; such as, for example,memory having feature sizes of less than or equal to about 20nanometers.

Example embodiments are described with reference to FIGS. 1-24.

Referring to FIG. 1, a construction 10 comprises an electricallyinsulative material 12 supporting a plurality of rails 14-18. The railsare elongated along a direction of an illustrated axis 5 in the shownembodiment, and such axis may be referred to as a first axis. Althoughthe rails are substantially straight in the shown embodiment, in otherembodiments the rails may be curved or wavy. Even if the rails arecurved or wavy, such rails may extend primarily along the illustratedaxis 5 in some embodiments.

The electrically insulative material 12 may comprise any suitablecomposition or combination of compositions, and in some embodiments maycomprise one or more of silicon nitride, silicon dioxide, and any ofvarious doped glasses (for instance, borophosphosilicate glass,phosphosilicate glass, fluorosilicate glass, etc.). The insulativematerial 12 may be supported over a semiconductor base (not shown). Suchbase may comprise, for example, monocrystalline silicon. If theelectrically insulative material is supported by a semiconductor base,the combination of the electrically insulative material 12 and theunderlying semiconductor base may be referred to as a semiconductorsubstrate, or as a portion of a semiconductor substrate. The terms“semiconductive substrate,” “semiconductor construction” and“semiconductor substrate” mean any construction comprisingsemiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials), and semiconductive materiallayers (either alone or in assemblies comprising other materials). Theterm “substrate” refers to any supporting structure, including, but notlimited to, the semiconductor substrates described above. In someembodiments, the insulative material 12 may be over a semiconductorconstruction which comprises a semiconductor base and one or more levelsof integrated circuitry. In such embodiments, the levels of integratedcircuitry may comprise, for example, one or more of refractory metalmaterials, barrier materials, diffusion materials, insulator materials,etc.

The rails 14-18 may comprise several stacked materials in someembodiments. The bottom material of the shown rails is an electricallyconductive material 20. Such electrically conductive material maycomprise any suitable composition or combination of compositions; and insome embodiments may comprise, consist essentially of, or consist of oneor more of various metals (for instance, tungsten, titanium, copper,etc.), metal-containing substances (for instance, metal nitride, metalsilicide, metal carbide, etc.) and conductively-doped semiconductormaterials (for instance, conductively-doped silicon, conductively-dopedgermanium, etc.). The electrically conductive material 20 formselectrically conductive lines 21 (only some of which are labeled)contained within the series of rails 14-18. Such electrically conductivelines may correspond to access/sense lines; and may, for example,correspond to wordlines or bitlines in some embodiments. The lines 21may be referred to as a first series of lines to distinguish them fromanother series of lines formed in subsequent processing.

The individual rails 14-18 comprise one or more materials over the lines21. The materials over lines 21 are diagrammatically illustrated asregions 22 (only some of which are labeled) over the individual lines21. Uppermost portions of the regions 22 comprise electricallyconductive material 24. The uppermost surface of material 24 mayultimately correspond to the top of a bottom electrode of a memory cell.In other words, the uppermost surface of material 24 may be a regionwhere a bottom electrode of a memory cell contacts memory cell material(described below); and thus material 24 may be referred to as bottomelectrode contact material.

Materials 20 and 24 may or may not comprise the same composition as oneanother. In some embodiments, materials 20 and 24 may be the sameconductive material as one another, and the intervening segment ofregion 22 may simply be more of the same conductive material. In otherembodiments, region 22 may comprise one or more materials suitable forfabrication into select devices (for instance, transistors, diodes,etc.)—with an example of such other embodiments being described belowwith reference to FIGS. 8-12.

Each of the rails 14-18 extends along multiple memory cell locations,with example memory cell locations 31-33 being labeled relative to therail 14. Ultimately, memory cells may be fabricated within such memorycell locations such that memory cell material of the memory cells isdirectly against the bottom electrode contact material 24 (as shown, forexample, in FIG. 7).

The rails 14-18 may be formed with any suitable processing. Forinstance, the various materials of the rails 14-18 may be formed acrosssubstrate 12, and a patterned mask (not shown) may be formed over suchmaterials to define locations of the rails 14-18. A pattern may then betransferred from the mask into the materials of the rails with one ormore suitable etches, and then the mask may be removed to leave theshown construction of FIG. 1. The mask may comprise any suitablecomposition or combination of compositions. For instance, the mask maycomprise photolithographically-patterned photoresist. As anotherexample, the mask may comprise one or more materials patterned utilizingpitch-multiplication methodologies.

In the shown embodiment of FIG. 1, the rails 14-18 are spaced from oneanother by intervening gaps. FIG. 2 shows dielectric material 36 formedwithin such gaps. The dielectric material may comprise any suitablecomposition or combination of compositions; and in some embodiments maycomprise, consist essentially of or consist of silicon dioxide. Theconstruction of FIG. 2 is shown to have a planarized surface 37extending across rails 14-18, and across the dielectric material 36.Such construction may be formed by initially forming dielectric material36 to fill the gaps between the rails 14-18, and to extend across uppersurfaces of the rails; and then utilizing chemical-mechanical polishing(CMP) to remove the dielectric material from over the rails and form theplanarized surface 37.

Referring to FIG. 3, an expanse of pad material 38 is formed across theplanarized upper surface 37, and an expanse of sacrificial material 40is formed across the pad material.

In some embodiments, the pad material may comprise a sacrificialmaterial provided as a buffer between the material 40 and the bottomelectrode contact material 24. In some embodiments, the pad material maybe omitted and the sacrificial material 40 may be provided directly onthe bottom electrode contact material. In some embodiments, the padmaterial may correspond to a memory cell material which is ultimatelyincorporated into memory cells. The memory cell material may be anymaterial either now known, or yet to be developed, which is suitable forutilization in cross-point memory. For instance, the memory cellmaterial may be a material suitable for utilization in one or more ofPCRAM, RRAM, CBRAM, PCM, etc. In some embodiments, the memory cellmaterial may comprise an oxide containing one or more of aluminum,antimony, barium, calcium, cesium, germanium, hafnium, iron, lanthanum,lead, manganese, praseodymium, ruthenium, samarium, selenium, silicon,strontium, sulfur, tellurium, titanium, yttrium and zirconium. In someembodiments, the memory cell material may comprise multivalent metaloxide; and may, for example, comprise, consist essentially of or consistof one or more of barium, ruthenium, strontium, titanium, calcium,manganese, praseodymium, lanthanum and samarium. For instance, themultivalent metal oxide may comprise, consist essentially of, or consistof calcium manganese oxide doped with one or more of Pr, La, Sr and Sm.In some embodiments, the memory cell material may comprisechalcogenide-type materials (for instance, materials comprisinggermanium in combination with one or more of antimony, tellurium, sulfurand selenium). In some embodiments, the memory cell material may includeadditional layers, such as an ion source material suitable forcontributing ions which ultimately form conductive bridges in PMCdevices. The ion source material may comprise, for example, one or bothof copper and silver; and may thus be configured for contributing coppercations and/or silver cations for formation of a conductive bridge. Forinstance, the ion source material may comprise a combination of copperand tellurium. The memory cell material may be a solid, gel, or anyother suitable phase.

Since the material 38 may be alternatively either a sacrificial materialor a memory cell material in some embodiments, the material 38 may bereferred to herein as a pad material, sacrificial material, or memorycell material in describing various different embodiments. The term “padmaterial” as utilized in referring to material 38 is generic relative tothe terms “sacrificial material” and “memory cell material.”

The sacrificial material 40 may comprise any suitable composition orcombination of compositions; and in some embodiments may comprise,consist essentially of, or consist of silicon (for instance, may consistof one or both of amorphous silicon and polycrystalline silicon).

Referring to FIG. 4, the sacrificial material 40 is patterned into aseries of lines 41-44. The lines 41-44 may be referred to as a secondseries of lines to distinguish them from the first series of linescorresponding to the lines 21 contained within the rails 14-18. Thelines 41-44 cross the rails 14-18; and in the shown embodiment aresubstantially orthogonal to the rails 14-18. Specifically, the lines41-44 are elongated along an axis 7, and the rails 14-18 are elongatedalong the axis 5 which is substantially orthogonal to the axis 7. Theterm “substantially orthogonal” is utilized to indicate that the twoaxes are orthogonal within reasonable tolerances of design andmeasurement.

The sacrificial material lines 41-44 are directly over the memory celllocations (for instance, the locations 31-33). The pattern of thesacrificial material lines 41-44 is transferred into the bottomelectrode contact material 24 to singulate such material into segments46 (only some of which are labeled). Each segment is associated withonly a single memory cell location. The pattern may be transferred intothe bottom electrode contact material with any suitable etch orcombination of etches.

The pattern of the sacrificial material lines is also transferred intothe one or more materials beneath the bottom electrode contact materialof the rails 14-18. Such singulates the regions 22 into pedestals (orpillars) 48 (only some of which are labeled). In embodiments in whichthe regions 22 comprise materials suitable for incorporation into selectdevices, the singulation of regions 22 into pedestals 48 may formindividual select devices. For instance, FIGS. 8-12 describe anembodiment in which the singulation forms individual diodes. The patternmay be transferred into the one or more materials of regions 22 with anysuitable etch or combination of etches. The pedestals 48 are capped withthe bottom electrode contact material 24, and are directly between thememory cell locations (for instance, the locations 31-33) and theconductive material 20.

The sacrificial material 40 may be patterned into the lines 41-44 withany suitable processing. For instance, a patterned mask (not shown) maybe formed over sacrificial material 40 to define locations of the lines41-44, a pattern may be transferred from the mask into material 40 withone or more suitable etches, and then the mask may be removed. The maskmay comprise any suitable composition or combination of compositions.For instance, the mask may comprise photolithographically-patternedphotoresist. As another example, the mask may comprise one or morematerials patterned utilizing pitch-multiplication methodologies. Themask may remain during the patterning of the materials of regions 22 insome embodiments, and may be removed prior to such patterning in otherembodiments.

The illustrated construction 10 at the processing stage of FIG. 4 has aplurality of trenches 51-53 formed between the lines 41-44. The trenches51-53 extend along the same direction as the lines 41-44. In someembodiments, the trenches 51-53 may be referred to as a first series oftrenches.

Referring to FIG. 5, dielectric material 54 is formed within thetrenches 51-53. Although a single dielectric material is shown, in otherembodiments multiple dielectric materials may be formed within suchtrenches. In some embodiments, the dielectric formed within the trenches51-53 may comprise one or both of silicon nitride and silicon carbide.The material 54 may be formed with any suitable processing, including,for example, one or more of atomic layer deposition (ALD), chemicalvapor deposition (CVD) and physical vapor deposition (PVD). In someembodiments, material 54 may be formed to extend across upper surfacesof lines 41-44, and may then be subjected to CMP to form the illustratedplanarized upper surface 55.

In the shown embodiment, the material 54 is deposited under conditionswhich leave voids 56 within trenches 51-53. Suitable conditions forleaving such voids are conditions in which the dielectric materialpinches off across the tops of the trenches before uniformly fillingcentral regions of the trenches. It can be advantageous that thedielectric provided within trenches 51-53 have a low dielectric constantin that such can alleviate or prevent cross-talk that may otherwiseoccur between memory cells on opposing sides of the trenches. Air has alow dielectric constant, and thus it can be advantageous to have theillustrated voids remaining within the trenches after formation ofdielectric material 54 within such trenches.

In some embodiments, the dielectric within the trenches 51-53 may bereferred to as dielectric lines 60-62. In the shown embodiment, suchdielectric lines comprise the illustrated voids 56 in combination withdielectric material 54. In some embodiments, the illustrated voids 56may consume at least about 10 percent of the volume of the dielectriclines formed within the trenches.

Although voids 56 are present in the shown embodiment, in otherembodiments the dielectric 54 may be provided to entirely fill trenches51-53. Thus, the voids may be omitted.

Referring to FIG. 6, sacrificial material 40 (FIG. 5) is removed toleave trenches 65-68. The trenches 65-68 may be referred to as a secondseries of trenches to distinguish them from the first series of trenches51-53 (FIG. 4). If the sacrificial material consists of silicon (forinstance, polycrystalline silicon), such may be removed utilizingtetramethylammonium hydroxide in some embodiments.

The trenches 65-68 are directly over the bottom electrode contactmaterial 24. In the shown embodiment, the formation of trenches 65-68exposes memory cell material 38. In other embodiments, material 38 maycorrespond to a sacrificial pad material which is removed from overbottom electrode contact material 24, and then replaced with memory cellmaterial. In yet other embodiments, material 38 may be omitted (asdiscussed above with reference to FIG. 3); and in such embodiments thememory cell material may be formed subsequent to the formation of thetrenches 65-68 to create the shown construction of FIG. 6.

The memory cell material 38 in the embodiment of FIG. 6 is configured asa planar sheet. If the memory cell material is deposited after removalof sacrificial material 40 (FIG. 5), the memory cell material may have adifferent configuration. For instance, FIG. 14 (discussed below) showsan embodiment in which memory cell material is configured asupwardly-opening container structures.

Although only the single memory cell material 38 is shown in theembodiment of FIG. 6, in other embodiments multiple memory cellmaterials may be utilized. The one or more memory cell materials may beany materials suitable for forming cross-point memory cells, either nowknown or later developed. For instance, the memory cell materials may besuitable for utilization in one or more of PCRAM, RRAM, CBRAM, PCM, etc.

Referring to FIG. 7, top electrode material 70 is formed within thetrenches 65-68. The top electrode material may comprise any suitablecomposition or combination of compositions, and in some embodiments maycomprise, consist essentially of, or consist of one or more of platinum,silver and copper. Accordingly, the top electrode material may comprise,consist essentially of, or consist of one or more noble metals. Asdiscussed above in the “background” section of this disclosure, it canbe difficult to pattern noble metals. However, in some embodiments thetrenches 65-68 enable utilization of a damascene process for patterningthe electrode material 70. Specifically, top electrode material 70 maybe formed to fill trenches 65-68 and to extend over dielectric lines60-62. The top electrode material may then be planarized (for instance,subjected to CMP) to remove the top electrode material 70 from over thedielectric material lines and thereby form the illustrated top electrodelines 71-74. Such top electrode lines extend along the axis 7, and thuscross the bottom electrode lines 21.

In some embodiments, the top electrode material 70 may comprise copper.In such embodiments, it may be desired for dielectric 54 to comprisecopper barrier material, such as one or more nitrides and/or it may bedesired for the conductive top electrode material to be surrounded byelectrically conductive barrier material.

Memory cells 76 (only some of which are labeled) are formed in thememory cell locations (for instance, the locations 31-33), with suchmemory cells having memory cell material 38 directly between the bottomelectrode contact material 24 and the electrode material 70. The memorycells may be considered to be configured as a memory array.

In some embodiments, the formation of the top electrode lines 71-74 maybe considered to be replacement of at least some of the sacrificialmaterial 40 of lines 41-44 (FIG. 5) with top electrode material 70. Inthe shown embodiment, all of the sacrificial material 40 of lines 41-44is replaced with electrode material 70. In some embodiments, memory cellmaterial may be formed within trenches 65-68 prior to formation of theelectrode material 70; and in such embodiments a portion of thesacrificial material 40 of lines 41-44 may be considered to be replacedwith the memory cell material, and another portion of the sacrificialmaterial 40 of lines 41-44 may be considered to be replaced with theelectrode material 70.

As discussed above, in some embodiments the materials of region 22(FIG. 1) may correspond to materials suitable for forming selectdevices. Example select devices are transistors (for instance, verticaltransistors) and diodes. FIGS. 8-12 illustrate an example embodiment inwhich region 22 comprises materials suitable for fabrication intodiodes.

Referring to FIG. 8, a construction 10 a is shown at a processing stageanalogous to that of FIG. 1. The rails 14-18 comprise stacks ofmaterials 20, 78 and 80. Such materials may correspond to suitablecompositions for a diode construction. For instance, materials 20, 78and 80 may be suitable compositions for a metal-silicon-metal diode(specifically, materials 20 and 80 may be metal, and material 78 may besilicon), or may be suitable compositions for a PIN diode (specifically,region 78 may be intrinsic semiconductor material, one of the regions 20and 80 may be n-type doped semiconductor material, and the other of theregions 20 and 80 may be p-type doped semiconductor material). Thebottom electrode contact material 24 is shown to correspond to a topsurface of material 80. In some embodiments, the bottom electrodecontact material may be a separate conductive material from the material80 of the diode compositions rather than being the shown top surface ofmaterial 80. Also, although conductive line 20 is shown to also be oneof the diode compositions, in other embodiments the line may be aseparate conductive material from the bottom diode composition.

The diode compositions 20, 78 and 80 extend along the memory celllocations (for instance, the locations 31-33).

Referring to FIG. 9, construction 10 a is shown at a processing stageanalogous to the above-discussed processing stage of FIG. 4.Accordingly, the pad material 38 and sacrificial material 40 have beenformed over rails 14-18, and then the construction has been subjected topatterning to form the lines 41-44 and the trenches 51-53. The formationof the trenches singulates diodes 82 (only some of which are labeled)from the diode compositions 20, 78 and 80. Specifically, the trenchesextend through materials 78 and 80 to form individual diodes underindividual memory cell locations (for instance, the memory celllocations 31-33). In embodiments in which the bottom diode compositionis a different conductive material from the material of the conductiveline 20, the trenches may extend through the bottom diode composition inaddition to extending through the diode compositions 78 and 80.

Referring to FIG. 10, construction 10 a is shown at a processing stageanalogous to the above-discussed processing stage of FIG. 5. Theconstruction comprises the dielectric lines 60-62 within the trenches51-53. Such dielectric lines comprise the voids 56 in combination withthe dielectric material 54 in the shown embodiment. The construction 10a also comprises the planarized upper surface 55.

Referring to FIG. 11, construction 10 a is shown at a processing stageanalogous to that discussed above with reference to FIG. 6. Thesacrificial material 40 (FIG. 10) has been removed to leave the trenches65-68 between the dielectric lines 60-62. The material 38 is at thebottoms of the trenches 65-68, and corresponds to memory cell materialof the type described above with reference to FIG. 6. In otherembodiments, the material 38 may be sacrificial material which isremoved and replaced with memory cell material, as discussed above withreference to FIG. 6.

Referring to FIG. 12, construction 10 a is shown at a processing stageanalogous to that discussed above with reference to FIG. 7. Topelectrode material 70 has been formed within the trenches 65-68 andpatterned to form the top electrode lines 71-74.

Memory cells 76 (only some of which are labeled) are formed in thememory cell locations (for instance, the locations 31-33), with suchmemory cells having memory cell material 38 directly between the bottomelectrode contact material 24 and the electrode material 70. Each memorycell is directly over one of the diodes 82.

The embodiment of FIGS. 8-12 singulates the diodes 82 during patterningof the memory cell material 38, which consolidates process stepsrelative to prior art processing. Such may improve throughput of afabrication process relative to prior art processes, and may eliminatemasking steps relative to prior art processes.

FIGS. 13 and 14 illustrate another example embodiment method.

Referring to FIG. 13, a construction 10 b is shown at a processing stageanalogous to that described above with reference to FIG. 6. However,unlike the embodiment of FIG. 6 which had the pad material 38 at thebottoms of the trenches 65-68, the embodiment of FIG. 13 does not havesuch pad material at the bottoms of such trenches.

Referring to FIG. 14, memory cell material 90 is formed within thetrenches 65-68 to line such trenches. The memory cell material formsupwardly-opening container structures within the trenches. Subsequently,top electrode material 70 is formed within such upwardly-openingcontainer structures and patterned to form the top electrode lines71-74.

In some embodiments, the memory cell material 90 may be formed as aplanar structure rather than as the container-shaped structure of FIG.14. For instance, FIG. 15 shows a construction 10 c at a processingstage analogous to that of FIG. 14, but in which the memory cellmaterial 90 has been formed as a planar structure.

In some embodiments, multiple memory cell materials may be utilized inthe memory cells. In such embodiments, the memory cell materials mayhave different shapes relative to one another. For instance, FIG. 16shows a construction 10 d utilizing two different memory cell materials92 and 94. The memory cell material 92 is configured as a planarstructure, and the memory cell material 94 is configured as acontainer-shaped structure provided directly over and directly againstthe memory cell material 92. The memory cell materials 92 and 94 may bereferred to as first and second memory cell materials, respectively.

In some embodiments, the memory cell material 92 may correspond to thepad material 38 of FIG. 6, and the material 94 may be provided withintrenches 65-68 prior to forming the top electrode material 70 of FIG. 7.In other embodiments, the memory cell materials 92 and 94 may both beformed within trenches 65-68 following a process stage analogous to thatof FIG. 13 so that neither of the memory cell materials corresponds tothe pad material 38 of FIG. 6.

The utilization of two memory cell materials may be useful in, forexample, forming PCM cells in which one of the memory cell materials isan ion source (for instance, a combination of copper and tellurium) andthe other is a switching region (for instance, an oxide or solid stateelectrolyte); forming RRAM cells in which one of the memory cellmaterials is a multivalent oxide and the other is a high k dielectric;etc. In some embodiments, more than two memory cell materials may beutilized.

In some embodiments, a construction analogous to that of FIG. 16 may beconfigured to have the electrode material 70 comprise copper, and thecontainer-shaped material 94 may comprise a copper barrier material(such as a nitride). In such embodiments, the material 94 may or may notbe a memory cell material.

FIGS. 17-23 illustrate another example embodiment method of fabricatingan array of memory cells. Referring to FIG. 17, a construction 10 e isshown at a processing stage analogous to that of FIG. 1. However, unlikethe construction of FIG. 1, the rails 14-18 include memory cell material38 and an electrically conductive material 100. The material 100 maycomprise any suitable composition or combination of compositions, and insome embodiments may comprise one or more of various metals (forinstance, tungsten, platinum, silver, copper, etc.), metal-containingcompositions (for instance, metal silicide, metal carbide, etc.) andconductively-doped semiconductor materials (for instance,conductively-doped silicon, conductively-doped germanium, etc.).Although only one memory cell material is shown, in other embodimentsmultiple memory cells may be provided between conductive materials 24and 100.

FIGS. 18-23 show the construction 10 e processed with methodologyanalogous to that discussed above with reference to FIGS. 2-7 to form anarray of memory cells (with such array comprising the illustrated memorycells 31-33 in FIG. 23). The memory cell material 38 of FIGS. 17-23 issingulated during the singulation of conductive material 24.Accordingly, each of the memory cells in the memory array of FIG. 23(for instance, the memory cells 31-33) comprises a segment of material38, with each segment of material 38 being associated with only a singlememory cell location. In contrast, the memory cell material 38 withinthe memory array of FIG. 7 is shown to be patterned into expanses whichextended across multiple memory cells. In the shown embodiment of FIGS.17-23, the conductive material 100 is patterned together with the memorycell material 38 to form segments of material 100 in one-to-onecorrespondence with the memory cells (for instance, the memory cells31-33).

The materials of region 22 (FIGS. 17-23) may correspond to materialssuitable for forming select devices. Example select devices aretransistors (for instance, vertical transistors) and diodes. FIG. 24illustrates an example embodiment in which region 22 comprises materialssuitable for fabrication into diodes. Specifically, FIG. 24 shows aconstruction 10 f at a processing stage analogous to that of FIG. 12,with construction 10 f comprising the singulated memory cell material 38and conductive material 100 discussed above with reference to FIGS.17-23. The regions 20, 78 and 80 may be regions of a diode (forinstance, region 20 may be an n-type doped region, region 78 may be anintrinsic region, and region 80 may be a p-type doped region, asdiscussed above with reference to FIGS. 8-12). In the shown embodiment,the memory cells 76 also comprise a conductive material 102 between thetop diode region 80 and the memory cell material 38. Such conductivematerial may be utilized to improve adhesion between of material 38,improve electrical transfer to material 38 and/or to improve otherproperties of the memory cells. The conductive material 102 may compriseany suitable composition or combination of compositions and in someembodiments may comprise one or more of various metals (for instance,tungsten, platinum, silver, copper, etc.), metal-containing compositions(for instance, metal silicide, metal carbide, etc.) andconductively-doped semiconductor materials (for instance,conductively-doped silicon, conductively-doped germanium, etc.). Thematerials 100 and 102 are shown to have different thicknesses relativeto one another, with material 100 being thicker than material 102. Inother embodiments, materials 100 and 102 may be about the same thicknessas one another, or material 102 may be thicker than material 100.

The memory cells and arrays discussed above may be incorporated intoelectronic systems. Such electronic systems may be any of a broad rangeof systems either now known or yet to be developed; with exampleelectronic systems being clocks, televisions, cell phones, personalcomputers, automobiles, industrial control systems, aircraft, etc.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

Some embodiments include a method of forming a plurality of memorycells. A series of rails is formed to extend along a first direction.Individual rails extend along multiple memory cell locations. Theindividual rails comprise bottom electrode contact material overelectrically conductive lines. The electrically conductive lines are afirst series of lines. An expanse of sacrificial material is formed toextend across the rails. The sacrificial material is patterned into asecond series of lines that extends along a second direction thatcrosses the first direction. A pattern of the second series of lines istransferred into the bottom electrode contact material to singulate thebottom electrode contact material into segments associated with onlysingle memory cell locations. At least a portion of the sacrificialmaterial of the second series of lines is replaced with top electrodematerial.

Some embodiments include a method of forming a plurality of memorycells. A series of rails is formed to extend along a first direction.Individual rails extend along multiple memory cell locations. Theindividual rails comprise bottom electrode contact material stacked overelectrically conductive lines. A series of sacrificial material lines isformed to extend along a second direction that crosses the firstdirection. The sacrificial material lines are directly over the memorycell locations. A pattern of the sacrificial material lines istransferred into the bottom electrode contact material to singulate thebottom electrode contact material into segments associated with onlysingle memory cell locations. A series of dielectric lines is formedbetween the sacrificial material lines. The dielectric lines extendalong the second direction. The sacrificial material lines are removedto leave trenches between the dielectric lines. The trenches aredirectly over the segments of the bottom electrode contact material. Topelectrode material is formed within the trenches and over the dielectricmaterial lines. The top electrode material is planarized to remove thetop electrode material from over the dielectric material lines andthereby form a plurality of top electrode lines directly over the memorycell locations. The top electrode lines extend along the seconddirection.

Some embodiments include a method of forming a plurality of memorycells. A series of rails is formed to extend along a first direction.Individual rails extend along multiple memory cell locations. Theindividual rails comprise bottom electrode contact material stacked overelectrically conductive lines. The electrically conductive lines are afirst series of lines. An expanse of sacrificial material is formed toextend across the rails. The sacrificial material is patterned into asecond series of lines which extend along a second direction thatcrosses the first direction. A pattern of the second series of lines istransferred into the bottom electrode contact material to singulate thebottom electrode contact material into segments associated with onlysingle memory cell locations. The transferring of the pattern forms aseries of first trenches that extend along the second direction.Individual trenches of the first series are between adjacent lines ofthe second series. One or more dielectric materials are formed withinthe first series of trenches. After said one or more dielectricmaterials are formed, the sacrificial material is removed to leave asecond series of trenches that extend along the second direction.Individual trenches of the second series are directly over the segmentsof bottom electrode contact material. Top electrode material is formedwithin the second series of trenches and over the one or more dielectricmaterials. The top electrode material is planarized to remove the topelectrode material from over the one or more dielectric materials andthereby form a plurality of top electrode lines that extend along thesecond direction.

Some embodiments include a memory array that comprises a first series ofelectrically conductive lines extending along a first direction. Pillarsare over the first series of electrically conductive lines. The pillarsare capped with bottom electrode contact material and are directlybetween the electrically conductive lines of the first series and memorycell locations. One or more memory cell materials are over the pillarsand within the memory cell locations. A second series of electricallyconductive lines extends along a second direction that crosses the firstdirection. The second series of electrically conductive lines comprisestop electrode material. The memory cell locations are directly betweenthe electrically conductive lines of the first and second series, andare in regions where the electrically conductive lines of the secondseries overlap the electrically conductive lines of the first series.The electrically conductive lines of the second series comprise one ormore of platinum, copper and silver.

Some embodiments include a memory array that comprises a first series ofelectrically conductive lines extending along a first direction. Pillarsare over the first series of electrically conductive lines. The pillarsare capped with bottom electrode contact material and are directlybetween the electrically conductive lines of the first series and memorycell locations. A first memory cell material is over the pillars andwithin the memory cell locations. The first memory cell material is aplanar sheet within the memory cell locations, and is directly againstthe bottom electrode contact material. A second memory cell material isover the first memory cell material. The second memory cell material isconfigured as a plurality of upwardly-opening containers that extendlinearly along a second direction that crosses the first direction. Asecond series of electrically conductive lines is within the containers.The second series of electrically conductive lines comprises topelectrode material. The memory cell locations are directly between theelectrically conductive lines of the first and second series, and are inregions where the electrically conductive lines of the second seriesoverlap the electrically conductive lines of the first series.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

We claim:
 1. A method of forming a plurality of memory cells,comprising: forming a series of rails extending along a first direction,individual rails extending along multiple memory cell locations, theindividual rails comprising bottom electrode contact material overelectrically conductive lines, the electrically conductive lines being afirst series of lines; forming an expanse of sacrificial materialextending across the rails; patterning the sacrificial material into asecond series of lines extending along a second direction that crossesthe first direction; transferring a pattern of the second series oflines into the bottom electrode contact material to singulate the bottomelectrode contact material into segments associated with only singlememory cell locations; replacing at least a portion of the sacrificialmaterial of the second series of lines with top electrode material; andwherein a first memory cell material is formed within the memory celllocations prior to forming the expanse of sacrificial material, andwherein a second memory cell material is formed within the memory celllocations by replacing a portion of the sacrificial material of thesecond series of lines with the second memory cell material.
 2. Themethod of claim 1 wherein the top electrode material comprises one ormore noble metals.
 3. The method of claim 1 wherein the top electrodematerial comprises one or more of platinum, copper and silver.
 4. Amethod of forming a plurality of memory cells, comprising; forming aseries of rails extending along a first direction, individual railsextending along multiple memory cell locations, the individual railscomprising bottom electrode contact material stacked over electricallyconductive lines; forming a series of sacrificial material linesextending along a second direction that crosses the first direction, thesacrificial material lines being directly over the memory cell locationsand in physical contact with the bottom electrode contact material;transferring a pattern of the sacrificial material lines into the bottomelectrode contact material to singulate the bottom electrode contactmaterial into segments associated with only single memory celllocations; forming a series of dielectric lines between the sacrificialmaterial lines, the dielectric lines extending along the seconddirection; removing the sacrificial material lines to leave trenchesbetween the dielectric lines, the trenches being directly over thesegments of the bottom electrode contact material; forming top electrodematerial within the trenches and over the dielectric material lines;planarizing the top electrode material to remove the top electrodematerial from over the dielectric material lines and thereby form aplurality of top electrode lines directly over the memory cell locationsand extending along the second direction; forming memory cell materialover the bottom electrode contact material within the memory celllocations prior to forming the top electrode material within thetrenches; and wherein at least some of the memory cell material isformed within the trenches.
 5. The method of claim 4 wherein the formingof the memory cell material within the trenches comprises forming planarsheets of the memory cell material along bottoms of the trenches.
 6. Themethod of claim 4 wherein the forming of the memory cell material withinthe trenches comprises forming upwardly opening container-shapedstructures of the memory cell material.
 7. A method of forming aplurality of memory cells, comprising: forming a series of railsextending along a first direction, individual rails extending alongmultiple memory cell locations, the individual rails comprising bottomelectrode contact material stacked over electrically conductive lines,the electrically conductive lines of the individual rails being indirect physical contact with an underlying insulative material; formingmemory material over the series of rails; after forming the memorymaterial, forming a series of sacrificial material lines extending alonga second direction that crosses the first direction, the sacrificialmaterial lines being directly over the memory cell locations;transferring a pattern of the sacrificial material lines into the bottomelectrode contact material to singulate the bottom electrode contactmaterial into segments associated with only single memory celllocations; forming a series of dielectric lines between the sacrificialmaterial lines, the dielectric lines extending along the seconddirection; removing the sacrificial material lines to leave trenchesbetween the dielectric lines, the trenches being directly over thesegments of the bottom electrode contact material; forming top electrodematerial within the trenches and over the dielectric material lines;planarizing the top electrode material to remove the top electrodematerial from over the dielectric material lines and thereby form aplurality of top electrode lines directly over the memory cell locationsand extending along the second direction; and wherein the segments ofthe bottom electrode contact material are along tops of select devices.8. The method of claim 7 wherein the select devices are transistors. 9.The method of claim 7 wherein the select devices are diodes which aresingulated during the singulation of the bottom electrode contactmaterial.
 10. A method of forming a plurality of memory cells,comprising: forming a series of rails extending along a first direction,individual rails extending along multiple memory cell locations, theindividual rails comprising bottom electrode contact material stackedover electrically conductive lines, the electrically conductive linesbeing a first series of lines; forming an expanse of sacrificialmaterial extending across the rails and in direct contact with an uppersurface of the bottom electrode contact material; patterning thesacrificial material into a second series of lines extending along asecond direction that crosses the first direction; transferring apattern of the second series of lines into the bottom electrode contactmaterial to singulate the bottom electrode contact material intosegments associated with only single memory cell locations; thetransferring of the pattern forming a first series of trenches thatextends along the second direction; individual trenches of the firstseries being between adjacent lines of the second series; forming one ormore dielectric materials within the first series of trenches; afterforming said one or more dielectric materials, removing the sacrificialmaterial to leave a second series of trenches that extends along thesecond direction; individual trenches of the second series beingdirectly over the segments of bottom electrode contact material; formingtop electrode material within the second series of trenches and over theone or more dielectric materials; planarizing the top electrode materialto remove the top electrode material from over the one or moredielectric materials and thereby form a plurality of top electrode linesextending along the second direction; and forming memory cell materialwithin the trenches of the second series prior to forming the topelectrode material within such trenches.
 11. The method of claim 10wherein the memory cell material forms upwardly-opening containerswithin the trenches of the second series; and wherein the top electrodematerial is formed within said upwardly-opening containers.
 12. A methodof forming a plurality of memory cells, comprising: forming a series ofrails extending along a first direction, individual rails extendingalong multiple memory cell locations, the individual rails comprisingbottom electrode contact material stacked over electrically conductivelines, the electrically conductive lines being a first series of lines;forming an expanse of sacrificial material extending across the rails;patterning the sacrificial material into a second series of linesextending along a second direction that crosses the first direction;transferring a pattern of the second series of lines into the bottomelectrode contact material to singulate the bottom electrode contactmaterial into segments associated with only single memory celllocations; the transferring of the pattern forming a first series oftrenches that extends along the second direction; individual trenches ofthe first series being between adjacent lines of the second series;forming one or more dielectric materials within the first series oftrenches; after forming said one or more dielectric materials, removingthe sacrificial material to leave a second series of trenches thatextends along the second direction; individual trenches of the secondseries being directly over the segments of bottom electrode contactmaterial; forming top electrode material within the second series oftrenches and over the one or more dielectric materials; planarizing thetop electrode material to remove the top electrode material from overthe one or more dielectric materials and thereby form a plurality of topelectrode lines extending along the second direction; and forming anexpanse of memory cell material across the rails, and forming theexpanse of sacrificial material over the expanse of memory cellmaterial; and wherein the pattern of the second series of lines istransferred into the expanse of memory cell material.
 13. The method ofclaim 12 wherein the memory cell material is a first memory cellmaterial, and further comprising forming a second memory cell materialwithin the trenches of the second series prior to forming the topelectrode material within such trenches.
 14. The method of claim 13wherein the second memory cell material forms upwardly-openingcontainers within the trenches of the second series; and wherein the topelectrode material is formed within said upwardly-opening containers.